Metal organo-phosphates



Patented Nov. 22, 1949 2,488,662

METAL onoA go-rnosgggl rgs Bruce B. Farrington, James 0. .Glaytomand Johns, T. Rutherford, Berkeley, Qal i t}, ess ignors to California Beseaijch. (,3, l 1 ln S -F 1 1 l m n ia e svr ii i wai No Drawing. Application June. 25,1946

Serial No.-.6'79,2,62:.

7 Claims. Cl. ZGO -AZQL 1 2 s-in n o relates to hi h molecula we h wateninsom le,,mineral il-s u l inca d miuinsal s of acid esters-of ph sph r a d The polyvalent metal salts of acid esters, of phosphoric acid have value'asimprovement agents, 5 for mineral lubricating; oils. Thus, .theyare efiec; tiveywhen usednalone to increase the resistance phosphate to .obta-in the esire of suchioils-to oxidation andithey have particular u the l I efat value' nwhenusedilin combination. with ;a polyvalent =;metal..salt;of .an alkylphenol, to inhibitlO of it 'is required 1 corrosionof alloy ibearingslsuch as copperelead It ls anobje'ct of the present, inv,ention, to pro; bearings' Sewimwxampla Famngton et eee lee n va en gnetal's,tsbrai' United States Patent-., -No. 2,228,659 andcNeelyu h 5511; et al.,United States-PatentNo.x2,228,6'71.

For convenience, these polyyalentmetal. salts of acid-esters of phosphoric acid wil-l-be frequently- L ""2, Y oi, the invention ,to provide. referred; to as polyvalent netalphosphatespd l'salts f acidfesters of Certain of thesepolyvalentmetal phosphates, phosp oric' "acid hIGIZLH IIB such-as the calciumand bariurnsalts, are waterwate r solii thaiilthealkalin earthfmetalsaltsfj solubleto a sufficient extent; or their solubilities of these ester'sandwhich aaiieieausas in mineral lubricating oils are sufficiently-40w; wear, (when used in mii leral, lubricating ils difiiculty is encountered in practice- Thus, I uoric 'ationxlasalf it isa common practice to disperse the polyvalent metal-phosphate in oil in relativelylarge amount, of the orderof 50% on the weight of oil-phosphate solution, to produce a concentrate or stock solution; This concentrate is stored a'nd shipp ed to be blended with" more oil to produce a finished product containing about 0.25 to 2.0% of phosphate.- The aforesaid calcium andbarium phosphates are difiicult to blend homogeneously ,iPFQHS ch co Thes Land.,otherllobiectsofthe invention will centrates; d er na ished oi sc ntainiaa lesser be apparentfffio mthe ensu ng ,iscripiibnianeij; amounts are prone to form emulsions 0n agitation the 'apbended claims. with ,water, or they may ,fail to ,pass, stringent We-l'iaiefdisco ifed that thezincandeadmium acceptance, tests which, i clude centrituging, 9 15,35 salts of'acid esteem phosphoricacidai'e superior}; h p ed. 7 v in that they .are'characterif zedby lowlw ater-solll Certain,other polyv n metaL- Q p atessu h v, bility jand .hi h ToihsOIubilityQj Moreover; they dog as the alminum phosphates, although more. 011; not ca e xcessiy ,wear'lof workin lbafls of soluble and less water-soluble, cause, some .diffi: machine I .lilbricat'edlby mineral, oil s; oont i i'fl culty, owing to wear. of working-partsoi internal 40 them, combustion engines, such ascylinder andpiston, The salts of the inventionarelof two types, d walls and'piston rings. v rived from the mono estersian Jthe (ll-esters:

Theabove-mentioned oil-Water solubility difi'ie culties can be solvediby. employing phosphoric, /0,-R 1 O,R1., esters of sufiiciently high moleculanweight aloe-V :y o= ,p hols or,phenols,-but{to obviate. these difliculties 3 fully it is necessary, by this means, to .useesteri q fying-- radicals of excessively high .molecula 1 'ea eis weight. These excessively highumolecular weight-m Mono-esters radicals are more expensive than.the. more, com mon radicals of lowermolecular weight, contain 7. $-9 mqn -gstersma bei pormal salts ing 5 to 20 carbonatoms. Also, the ester ifying. I (Ml-511904) or acld salts QQ@=; radical functions primarily as-an oil-solubilizingf. In theabpyertormulaaRrandRz-arehydrocarbon t-4 t e e t ven b in }a ac a o h --.l e lsnwhic .m b subs it ted;l wereab e s h t i m arte brit a-zim e ei meta nshr r o s bs itueu..mnc M11 s n .l uszea eua sf .-ti e teatthe sa iainae a i salt .maye 59llq i i rmeqli ema either the monoor the ii-esters. Normal salts of the types R1 R1 o t t o=r M o=r '-o-M-o-i =o PM t ILA are preferred, and of these the salts of the diesters are preferred as being more oil-soluble. The radicals R1 and R2 contain each not less than 5 carbon atoms, preferably not less than carbon atoms, and preferably not more than carbon atoms. These radicals may be alkyl (e. g., amyl, hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and eicosyl), alkylene (e. g., octenyl, hexadecenyl), cycloaliphatic (e. g., napthenyl, cyclohexyl and methylcyclohexyl), aryl (e. g., phenyl), alkaryl (e. g., methylphenyl and cetyl phenyl), or aralkyl (e. g., benzyl, phenylstearyl and cetylbenzyl) radicals. Saturated aliphatic and cycloaliphatic radicals and aryl radicals substituted by one or more saturated aliphatic or cycloaliphatic radicals are preferred.

Mixed radicals, e. g., alkyl-cycloaliphatic and alkylalk-aryl, may be used. Likewise, mixed salts of monoand di-esters may be used, c. g., mixed zinc salts of mono-cetyl phosphoric acid and dicetyl phosphoric acid.

The parent esters of the salts of the invention can be prepared by methods :well known in the art. Certain of the parent esters, e. g., monoand dicetyl phosphates and monoand dicholesteryl phosphates are described in the literature. Exemplary methods of preparation are provided by the specific examples below and by Plimmer and Burch, Journal of the Chemical Society, 1929, pages 279-291.

The zinc and cadmium salts can be readily prepared from the parent esters, or from alkali metal salts of the same, by methods well known in the art, as exemplified by the specific examples and by Plimmer and Burch, op. cit.

Examples of salts of the invention are: normal zinc and cadmium mono-amyl phophates, normal zinc ,and cadmium mono-octyl phosphates, normal zinc and cadmium mono-lauryl phosphates, normal zinc and cadmium mono-eicosyl phosphates, normal zinc and cadmium mono-methylcyclohexyl phosphates, normal zinc and cadmium mono-benzyl phosphates and normal zinc and cadmium mono-cetylphenyl phosphates; also, the corresponding normal zinc and cadmium di-amyl, di-octyl, di-lauryl, di-eicosyl, di-methylcyclohexyl, di-benzyl and dicetylphenyl phosphates.

The following specific examples will serve further to illustrate the preparation and properties of the salts of the invention.

EXAMPLE 1 Monoand di-cetyl phosphoric acids and zinc and cadmium salts of the same A mixture of monoand dicetyl phosphoric acids was prepared by reacting 76 parts by weight of cetyl alcohol with a mixture of 17 parts of phosphorus pentoxide and 7 parts of pyrophosphoric acid at 270 F. The phosphorus pentoxide and pyrophosphoric acid were slowly added to the cetyl alcohol. The reaction was complete in two hours.

The two acids were separated by dissolving in hot alcohol (to 20% concentration) and cooling to 40 F., causing precipitation of all the di-ester. The mono-ester was extracted from the alcoholic solution by means of aqueous KOH and the acid was freed by acidification with hydrochloric acid. The dicetyl phosphoric acid was recrystallized twice from ethyl alcohol and once from absolute alcohol. It had a melting point of 63-64.5 C. and analyzed 5.78% phosphorus (theory 5.6%). The monocetyl phosphoric acid analyzed 9.73% phosphorus (theory 9.64%).

Both acids were white crystalline materials, the mono-ester having a flaky appearance and the diester, a granular appearance.

To prepare zinc monocetyl phosphate, the potassium salt was reacted with an equivalent amount of zinc chloride in alcohol solution at 150 F. over a period of 5 hours. The mixture was then cooled to precipitate white zinc monocetyl phosphate, which was washed with hot water to remove potassium chloride and unreacted zinc chloride, as shown by the appearance of only a faint cloud on treating cc. of filtrate with 10 cc. of 0.05 N silver nitrate. The salt was then washed with hot ethyl alcohol and dried in a desiccator at reduced pressure.

To prepare zinc dicetyl phosphate, dicetyl phosphoric acid was reacted with zinc oxide under reflux for 7 hours, in a solvent consisting of two parts by volume of benzene and one of ethyl a1- cohol. The desired salt was obtained as a solid precipitate and was washed with ethyl alcohol and extracted with hot benzene. The benzene was evaporated and the precipitated salt was dried under reduced pressure. Analysis: Found, per cent Zn, 5.9; per cent P, 5.4. Theory, per cent Zn, 5.6; per cent P, 5.4.

Cadmium mono-cetyl phosphate was prepared and purified in the same manner as the corresponding zinc salt, cadmium chloride hydrate eing used in place of zinc chloride. Analysis: Found per cent Cd, 29.1; per cent P, 6.6. Theory, per cent Cd, 25.9; per cent P, 7.2.

Cadmium dicetyl phosphate was prepared by reacting potassium dicetyl phosphate with an equivalent amount of cadmium chloride hydrate in alcohol at 150 F. The solid reaction product was washed with ethyl alcohol, dried, washed with hot benzene, recovered from benzene solution by evaporation of the solvent and dried under reduced pressure.

EXAMPLE 2 Mono-tart. amylphenyl phosphoric acid and zinc and cadmium salts of the same p-Tert. amylphenol was reacted with an equivalent amount of phosphorus pentoxide at 300 F. for 3 hours. The reaction product was purified by recrystallization from petroleum ether to give white, flaky crystals, melting point 210-214 F. The zinc salt was prepared by refluxing one molecular proportion of the acid with 0.68 molecular proportion of zinc oxide in a solvent consisting of two parts by volume of benzene and one of ethyl alcohol for six hours. The solid reaction product was washed with 5% aqueous acetic acid to remove unreacted zinc oxide, then with ethyl alcohol to remove unreacted acid, and dried under reduced pressure.

The cadmium salt was prepared by reacting the potassium salt of mono-p-tert. amylphenyl phosphoric acid with an equivalent amount of cadmium chloride hydrate at F. in ethyl alcohol. The solid reaction product which separated on cooling the mixture to room temperature was washed successively with water and ethyl alcohol to remove potassium chloride, and unreacted cadmium chloride and acid.

Properties of the various salts of the examples are given in Table I below.

These salts were all oil-soluble, the salts of mono-esters being least oil-soluble and the salts of di-esters being most oil-soluble. In general, salts of esters containing a total of at least 20 carbon atoms are freely oil-soluble, those containing less than this being more sparingly oilsoluble.

Interatomic distances of the parent esters, and of the salts of Table I, were determined, establishing the identity of the salts. These interatomic distances, as determined by X-ray diffraction patterns, are as follows:

6 241,648, filed November 31, 1938, since issued on January 14, 1941 as United States Patent No. 2,228,659.

We claim:

1. A zinc salt of an acid ester of ortho phosphoric acid, wherein each esterifying radical is a hydrocarbon group containing not less than 5 carbon atoms.

2. A zinc salt of an acid ester of ortho phosphoric acid, wherein each esterifying radical is a hydrocarbon group containing 5 to 20 carbon atoms, and said salt contains a total of not less than 10 carbon atoms.

3. A zinc salt of an acid ester of ortho phosphoric acid, wherein each esterifying radical is an alkyl hydrocarbon group containing 5 to 20 carbon atoms.

4. A zinc salt of an acid ester of ortho phosphoric acid, wherein each esterifying radical is a cycloaliphatic hydrocarbon group containing 5 to 20 carbon atoms.

5. A zinc salt of an acid ester of ortho phosphoric acid, wherein each esterifying radical is an alliaryl hydrocarbon group containing up to 20 carbon atoms.

6. The salts of claim 2, wherein said acid ester is a mono-ester.

TABLE II Interatomic distances Mono-p-tert. Zn Cd Mono-cetyl Dl-cetyl Zn Cd Zn Cd Compound phosphoric phosphoric $333 1??? mono-cetyl mono-cetyl dicetyl dicet gg fi gg gfigfggggg acid acid acid phosphate phosphate phosphate phosphate phosphate phosphate Distance in Angstrom units (I) and relative line intensities (II) per 0.

Further examples of methods of preparing salts of the invention are as follows:

EXAMPLE 3 Zinc and cadmium dicyclohexyl phophates The parent acid ester is prepared by heating cyclohexanol with phosphorus pentoxide. The salts are prepared by precipitating them from an aqueous solution of the sodium or potassium salt of the parent acid, by addition of cadmium chloride or zinc acetate.

EXAMPLE 4 Zinc and cadmium naphthenyl phosphates These are prepared by reacting naphthenyl alcohols (from reduction of naphthenic acids) with phosphorus pentoxide and precipitation of the desired salts from an aqueous solution of alkali metal salt of the parent acid ester by addition of cadmium chloride or zinc acetate.

This application is a continuation-in-part of our copending application Serial No. 374,245, filed January 13, 1941 (now abandoned) which in turn is a continuation-in-part of application Serial N o. 75 1917, 3rd

7. The salts of claim 2, wherein said acid ester is a di-ester.

BRUCE B. FARRINGTON. JAMES O. CLAYTON. JOHN T. RUTHERFORD.

REFERENCES CITED The following references are of record in the OTHER REFERENCES Plimmer et a1., Jour. Chemical Soc. (London), pgs. 279-291 (1929).

Smiths, Introduction to Inorganic Chemistry,

Ed., pg. 763. 

